If dynamic damage of an existing part surface on active service cannot be sensed, it is impossible to learn the worn state of the part surface.
Current part surface fatigue wear tests mostly take variation of the factors such as vibration, frictional coefficient, and temperature as a judging basis for evaluating worn state of part surfaces. When the actual value of the selected judging factors exceeds a pre-determined threshold value, it indicates failure of the part surface. Afterwards, the failed part is subjected to fracture analysis to reversely infer the mechanism of failure by experience or classical theory. However, such ex-post judgment of failure and mechanism study cannot estimate critical failed state of part surfaces. Hence, a controlling mechanism capable of dynamically monitoring and controlling failure of part surface is impossible to be established.
Smart sensing elements can real-time monitor the worn state of part surfaces, thus, it is preferred to arrange smart sensing units on part surfaces.
Piezoelectric sensor that is manufactured unitizing the piezoelectric effect of piezoelectric materials is a kind of smart sensing unit used commonly at present. In the course of applying piezoelectric sensors to mechanical facilities, it is necessary to adhere piezoelectric sensors to the facilities (or parts).
Whereas, some mechanical facilities have complicated structures or work in severe environments, which causes poor binding between the piezoelectric sensors and facilities (or parts), resulting in low detection precision of the piezoelectric sensors, or even fall-off of piezoelectric sensors.